“My sister has raised two extraordinary daughters,” the 36-year-old exclusively told Us Weekly of his older sister, Maggie Gyllenhaal. “They are so well behaved and they are so thoughtful and they are so observant of the world around them and I’m so proud of not only them but my sister as a mother. When they come to me I get two great girls [but], you know, at the end of the day there are times where it’s not bad to hand them back.”

Peter Sarsgaard and Maggie Gyllenhaal attend "The Magnificent Seven" premiere at the Museum of Modern Art on September 19, 2016 in New York City.Jamie McCarthy/Getty Images

“When I’m with them all I can think about is what incredible work my sister has put in and what a good mother she is with all the things she has on her plate already,” Jake, added to Us. “With her extraordinary talent and everything she does there, it says a lot about her and it says a lot about her husband. Fully devoted to their family. They give me a chance to be a fun uncle because their daughters are so cool.” (He is also the godfather of Michelle Williams and Heath Ledger’s11-year-old daughter Matilda.)

The Southpaw star portrays Jeff Bauman in the David Gordon Green-directed biographical drama opposite Tatiana Maslany. Bauman lost both of his legs during the Boston marathon terrorist attack in April 2013.

Jeff Bauman and Jake Gyllenhaal attend the "Stronger" New York Premiere at Walter Reade Theater on September 14, 2017 in New York City.Eugene Gologursky/FilmMagic
Jake Gyllenhaal’s Love Life

“I think Jeff’s story is extraordinary and I tried to give all of myself to it, or as much as I could without losing myself, which I felt like maybe sometimes I did,” Jake told Us on Thursday night. “I knew it was in service of not only Jeff, also all the people who are survivors. And when I say survivors I don’t mean of terror bombings, I mean of survivors in general.”

“I don’t look at the world in the same way [anymore],” he continued. “Now [Jeff] walks like five miles. But we walk slower. He said to me the other day, ‘You walk a little slower,’ and I said ‘Yeah.’ And he said, ‘Yeah, you know you smell more, you see more, you experience more when you walk just a little slower.’ And I think that’s one of the many things that I realized, learning about him, spending time with him and having the honor of playing him. Just stop and slow down and appreciate your life.”